SYMPTOMS AND SIGNS

Kernels are discolored or
blackened, usually at the embryo (germ) end. The entire kernel, or just a
portion of it, can be discolored. Although usually not yield-reducing, black
point can reduce grade and quality. In U.S. wheat standards, blackened kernels
are considered damaged, and only 2% are permitted in wheat graded as US No.1,
and 4% in US No.2. Black point is especially important on durum wheat because
black specks can appear in the semolina, making it undesirable for further
processing.

COMMENTS ON THE DISEASE

Black point is a disease that affects wheat and barley; it is most
important on durum wheat. It is caused by several common fungi. These fungi are
most troublesome when the relative humidity exceeds 90%. Expanding green
kernels are most susceptible, while premature seed senescence also promotes
black point. The fungi that cause black point often occur on kernels that do
not show symptoms of black point. Some factor(s) related to moisture,
temperature, and plant growth or senescence triggers the infection that results
in symptom expression. High humidity or rainfall from anthesis to soft dough,
high nitrogen fertility, excessive late season irrigation, and lodging usually
are associated with high levels of the disease.

MANAGEMENT

Black point can be partially controlled by reducing irrigation
frequency after heading and by reducing nitrogen rates, without sacrificing
either yield or quality. Because black point can occur at damaging levels in
some seasons despite modifications in cultural practices, the best option for
control is to combine reduced input practices with black point resistant
cultivars. Current cultivars differ in the level of resistance or tolerance to
the disease, although there are no completely resistant cultivars available.

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